Sound apparatus



Feb. 2,1937. w. KUNZE 2,069,254

' SOUND APPARATUS Filed Feb. 24. 1930 A TTORNE? Patented Feb. 2, 1937PATENT OFFICE 2,069,254 scum) APPARATUS Willy Kunze, Bremen, G

,assignorto ermany Submarine Signal Company, Boston, Mass a corporationof Maine Application February 24, 1930, Serial No. 430,929 In GermanyMarch 1, 1929 2 Claims.

The present invention relates to sound receiving apparatus, particularlyfor use in submarine signaling, and more particularly for use where aplurality of receiving units must be employed together and have adefinite relation with one another.

It is often necessary, in systems of the type above mentioned, tomaintain definitely for a sound receiver a fixed tuning, damping andsensitivity. This has been done in the past in various manners, amongthe most common methods being the use of damping'means, as for instance,rubber, which can be pressed against the diaphragm and by which thediaphragm can be damped and its sensitivity adjusted in the fash- .iondesired. --In such means, however, after in-.

stallation it is difilcult to change the damping for practical reasons,and when, through deterioration oi the rubber or other ways, thecharacteristics of the unit change, it is impossible be controlledelectrically, as will be explained.

The invention will be more fully described in connection with thedrawing, which shows an embodiment of the same. The electrodynamichydrophone or receiver '35 comprises a diaphragm 4, mounted in a casingl3, and having attached thereto a frame l4,

on which is the winding 3. This winding is situated in a circularmagnetic field which is formed by the magnets I and 2, the magnet 2being the center core surrounded by the pole pieces of the magnet I. Thecoil 3 is connected through the capacity 8 and transformer 9, Ill.to thetelephone ll, whereby a signal received by the diaphragm 4 may be heard.

In parallel thereto is the choke I, the battery 5 and the resistance 6,whereby a direct current may be impressed upon the winding 3. Thiscurrent will cause a definite pull upon the diaphragm I and also furnisha definite amount of damping,

depending upon the direct current value in the coil 3 and the strengthof the magnetic field.

I It is also possible to use between the diaphragm 4 and the field pieceI a rubber cushion l 2 against which the diaphragm 4 may be pulled bymeans 5 of the direct current passing through the winding 3.

By means of the adjustable resistance 5, which may be controlled fromthe position of the telephone I I, the value of the current can bechanged 10 to attain the correct amount of damping which is desired.

What is claimed is:

1. An electrodynamic converter' comprising means for producing amagnetic field, a dia- 16 phragm, a coil fixed to said diaphragm andextending into said magnetic field, mechanical damping means comprisinga solid yielding elastic compressible material adapted to be compressedby said diaphragm, said means being at- 20 tached on the one side tosaid diaphragm, means presenting a substantially rigid surface touchingsaid damping means on the other side and means for variably controllingthe effect of said damping means comprising said coil, a source of elec-25 tric current and adjustable means for varying the current in saidcoil, for compressing the said damping means, said coil serving tocooperate with the magnetic field to convert acoustic to electricenergy.

2. An electrodynamic converter comprising means producing a cylindricalmagnetic field, a coil located in said field, a diaphragm positionednormal to the coil and attached thereto, means supporting the diaphragmnear its periphery, a 35 rubber damping ring positioned in the inside ofthe diaphragm, means positioned behind said damping means forrestraining the motion thereof, a source of direct current and means forimpressing the same upon said coil, said coil serv- 40 ing to cooperatewith the magnetic field to convert acoustic to electric energy.

.W'ILLYKUNE.

